Switch apparatus



y 1 1 59 R J. SCHNEDER 2,895,032

SWITCH APPARATUS Filed May 2'7, 195'? INVENTORI v RALPH J. SCHNEIDER ATTO/MEY United States Patent SWITCH APPARATUS 'Ill., assignor to Minne- Ralph J. Schneider, Freeport,

Minneapolis,

apolis-Honeywell Regulator Company, Minm, a corporation of Delaware The present invention is directed to fluid metal switches, particularly mercury switches, wherein means are provided to allow the passage of gas contained within an elongated switch envelope around a globule of the fluid metal also contained within the switch envelope, which globule of fluid metal would normally occupy the entire lateral cross-section of a portion of a similar switch envelope without the aforementioned means.

In miniaturizing fluid metal switches, essentially two problems arise. First, when-utilizing an elongated envelope having a relatively small enclosure with a globule of fluid metal within the enclosure, adhesion arises between the surface of the enclosure and the surface of the globule of fluid metal so that movement of the fluid metal upon a tilting of the envelope is retarded. This problem can be overcome in a number of ways. Two of the expendients which can be utilized are coating a surface of the enclosure with a dry film or adding a slick fill. to the globule of fluid metal. Both of these expedients result in a lubricant being provided between the surface ofthe enclosure and the surface of the globule of fluid metal. Other expedients can be utilized to overcome the-problem of surface tension. However, as these are well known by 'those'skilled in the art, no further mention of them will be made here. elongated envelope having a relatively small cylindrical enclosure with a globule of fluid metal, there is a tendency for the globule of fluid metal to completely occupy the lateral cross-section of a portion of the enclosure. It should be remembered that the globule of fluid metal disposed within the envelope must be of sufficient mass as to be able to carry the required electrical load and must be of suflicient mass as to be consistent in itsaction when the envelope is tilted, that is, the movement of the globule of fluid metal should be smooth and regular and not be inhibited by frictional forces between the periphery of the enclosure and the globule of fluid metal. If these two considerations were not of importance, the mere reduction in the size of the envelope and the enclosure would be suflicient and would provide the desired result of a miniature device. The forementioned tendency of the globule of fluid metal to completely occupy a portion of the enclosure results in two separate pockets being set up, one at either extremity of the globule. It may be here noted that in mercury switches these pockets contain an arc extinguishing gas, such as hydrogen. However, depending upon the particular type of device, any appropriate gas may be contained in the pockets.

Upon a tilting of the envelope, the globule of fluid metal is moved in the appropirate direction. However, the fluid metal in so moving causes a decrease in the volume and hence an increase in the pressure of the gas in the pocket against which the globule of fluid metal is moving, thereby retarding and finally stopping further movement of the globule of fluid metal in the appropriate direction. It is this second problem and its solution by the advancement disclosed herein which is the subject of the present application. 7 r

Second, when utilizing an "ice Since, in a fluid switch of the type under consideration, it is the lack of communication between the gas pockets disposed at either'extremity of a globule of fluid metal which is the main problem, it is obvious that the problem can be alleviated by including in a fluid switch means which at all times provide a gas passage between the gas pockets. This can be brought about by providing an envelope with an obstruction located within the enclosure and extending substantially the length of the enclosure, or by providing an envelope with a discontinuity in the peripheral surface of the enclosure extending substantially the length of the enclosure. This obstruction or discontinuity when coacting with the globule of fluid metal provides a gas passage past the fluid globule thereby connecting the gas pockets by utilizing the meniscus eflect arising between the obstruction or discontinuity and the globule of fluid metal. The obstruction or discontinuity mentioned above can be, for example, in the form of a depression or ridge located in the compartment peripheral surface or can be in the form of one of the electrodes of the fluid switch or can be in the form of an elongated foreign body disposed loosely in the compartment.

It is an object of this invention provide a miniature fluid device, the function of which is unaffected by the gas contained within the envelope thereof.

It is another object of the invention to provide a miniature fluid metal electrical device wherein a gas passage is provided across the globule of fluid metal contained within the envelope thereof.

It is a further object of this invention to provide a dis continuity in the periphery of, or an obstruction disposed within the enclosure formed by the envelope of a fluid switch to cooperate with the globule of fluid metal disposed within the enclosure to provide a gas passage around the globule of fluid metal.

These and other objects will become more apparent from a reading of the following specification and appended claims wherein:

Figure l is a longitudinal cross sectional view of a fluid switch incorporating the patentable advancement disclosed herein;

Figure 2 is a lateral cross sectional view along lines 22 of Figure 1;

Figure 3 is a longitudinal cross sectional view of a fluid switch showing a modification of the invention; and

Figure 4 is a lateral cross sectional view along lines 4-4 of Figure 3.

Referring to Figures 1 and 2, a fluid metal switch is shown including an envelope 10 in the form of a cylindrical glass container. The envelope 10 encompasses a cylindrical enclosure or compartment 11. An electrode 12 in the form of a cylindrical wire includes a portion disposed and secured in an end portion of the envelope 10. The electrode 12 includes a further portion which extends substantially the entire length of the compartment 11 and is disposed proximate to a peripheral wall surface of the compartment 11. An electrode 13 in the form of a cylindrical wire includes a portion disposed and secured in the end portion of envelope 10 and further includes a portion disposed within the compartment 11. A globule of fluid metal 14, such as mercury or sodium-. potassium, is located within the compartment 11 and is arranged to coact with the electrodes 12 and 13 to perform the switching function.

It will be noted in Figure 2 that the globule of fluid metal 14 is shown as occupying a major area of the cross section of the compartment 11. As was mentioned previ? ously, the present invention is directed to devices utilizing. relatively small envelopes having a globule of fluid metal disposed therein which, without incorporating the concepts of the present invention, would normally occupy the en-...

. Patented July 14, 1959 tire lateral cross sectional area of a portion of the compartment thereof.

While the drawing shows the switch apparatus to be relatively large, it should be appreciated that switch appar'atus of the type shown has been constructed wherein the overall length of the envelope is approximately of an inch, the outside diameter of the envelope is approximately of one inch, and the inside diameter of the envelope is approximately of an inch. These dimensions are not to be taken as limiting, but merely as illustrative of a device constructed utilizing the concepts disclosed herein.

With a miniature envelope of the general configuration described above, but not including the portion of electrode 12 which extends substantially the length of compartment 11or a similar obstruction or discontinuity in the peripheral surface of the compartment, a globule of fluid metal, sufiicient to provide an operative switch apparatus, disposed within the compartment of the envelope normally completely occupies a lateral cross-section of a portion of the compartment. This, of course, blocks or interferes with communication between the gas pockets disposed at either extremity of the globule of fluid metal. Thus, upon a tilting of the envelope, the globule of fluid metal, due to the action of gravity, moves in the appropriate direction against the appropriate pocket of gas and results'in the volume and pressure of the gas in the pocket under consideration being decreased and increased, respectively, until such a time as the force of the gas equals the opposing force due to the gravitational effect of the globule of fluid metal, whereupon further movement of the globule of fluid is stopped. This limitation in the movement of the globule of fluid metal, of course, interferes with the operation of the switch apparatus.

The incorporating of electrode 12, as shown in Figures 1 and 2, in combination with a relatively small compartment 11 along with a globule of fluid metal 14, which would normally occupy the lateral cross section of a portion of a similar compartment without the electrode 12, results in a phenomenon occurring whereby the meniscus effect arising due to the coaction between the electrode 12 and the globule of fluid metal 14 provides a depression in the globule of fluid metal so that air passages are created on either side of the electrode 12 which connect the gas pockets located at either extremity of the globule of fluid metal 14. It can be seen that with such an arrangement the size of a fluid switch apparatus is not limited by the diameter of the compartment wherein the globule of fluid metal is contained as the obstruction or discontinuity provided within the compartment is suflicient to bring the meniscus effect arising due to the coaction between the electrode 12 and the globule of fluid metal 14 into play causing a passage to be set up across the globule of fluid metal interconnecting the gas passages at either extremity of the globule of fluid metal.

In Figures 3 and 4 a modification of the invention is shown. An envelope 20 encompassing an enclosure or compartment 21 is provided with a pair of electrodes 22 and 23, a portion of each of which are disposed within the compartment 21. A globule of fluid metal 24 is also provided in the compartment 21. Instead of one of the electrodes extending substantially the length of compartment 21, a ridge or inwardly extending depres sion 26 is provided by the deformation 25 provided in the outer periphery of the envelope 20.

It will be noted that the ridge or depression 26 is located at the bottom of the compartment 21, as opposed to the disposition of the electrode 12 in Figures 1 and 2, however, the inter-relation between the globule of fluid metal 24 and the ridge or depression 26 is substantially the same. That is, the globule of fluid metal 24, which would, without the ridge 26 being present, completely occupy a lateral cross section of a portion of the compartment 21, cooperates with the ridge or depression 26 so as to provide passages interconnecting the gas pockets disposed at either extremity of the globule of fluid metal.

In both arrangements disclosed herein it will be noted that an obstruction or discontinuity is provided in a compartment wherein a globule of fluid metal is disposed. The obstruction located within the compartment or the discontinuity, or the obstruction in the peripheral wall surface of the compartment cooperates with the globule of fluid metal and the meniscus effect resulting therefrom to provide depressions in the fluid metal to allow passage of gas across the globule of fluid metal from one gas pocket to the other. While the arrangement disclosed herein shows the obstruction or discontinuity proximate to a peripheral surface of the compartment, the obstruction or discontinuity could be removed from the peripheral surface to a much greater degree. The arrangements shown are merely illustrative and there are, of course, other envelope and compartment configurations not presented here which would provide the same result which are displayed by the arrangements disclosed therein. Therefore, to determine the scope and breadth of the invention, reference should be made to the following claims.

I claim:

1. A mercury switch comprising: an elongated glass envelope encompassing a substantially cylindrical compartment, said envelope being deformed in a longitudinal direction to provide a longitudinal inwardly extending ridge in said compartment; a globule of mercury disposed within said compartment, said globule of mercury being of such a mass as would normally occupy the entire lateral cross section of a portion of a similar compartment without said ridge; the ridge and the compartment of said envelope and said globule of mercury and the meniscus eifect resulting therefrom cooperating to provide a gas passage across said globule and a pair of wire electrodes, a portion of each being disposed within said compartment and arranged to coact with said globule of mercury.

2. A mercury switch comprising: a non-conducting envelope encompassing a compartment, said envelope being deformed in a longitudinal direction to provide a longitudinal inwardly extending ridge in said compartment; a globule of mercury disposed within said compartment, said globule of mercury being of such a mass as would normally occupy the entire lateral cross section of a portion of a similar compartment without said ridge; the ridge and the compartment of said envelope and said globule of mercury and the meniscus effect resulting therefrom cooperating to provide a gas passage across said globule and a pair of electrodes, each having a portion disposed within said compartment and arranged to coact with said globule of mercury.

3. An electric switch comprising: an elongated envelope, globule of conducting liquid having a high cohesive force within said envelope; and a gas filling other portions of said envelope, said envelope having an internal surface irregularity extending throughout the length thereof of such configuration that the cohesive force of the liquid prevents the liquid from completely conforming to the irregularity, the remaining portion of the irregularity containing said gas.

4. For an electrical device: a non-conducting envelope encompassing a substantially cylindrical enclosure, said envelope being deformed along its length so as to provide an inwardly extending peripheral portion within said enclosure; and a globule of liquid metal disposed within said enclosure, said globule being of such a mass as would normally block the passage of gas contained within the enclosure past the globule in a similar envelope without said inwardly extending peripheral portion, said inwardly extending peripheral portion and said globule of liquid metal and the meniscus effect resulting therefrom cooperating to provide a gas passage across said globule 5. For an electrical device: a non-conducting envelope encompassing a substantially cylindrical enclosure, said envelope being deformed along its length so as to provide a discontinuity in the periphery of said enclosure; and a globule of fluid metal disposed within said enclosure, said globule being of such a mass as would normally interfere with the passage of gas contained Within the enclosure past the globule in a similar envelope without the said discontinuity, said discontinuity and said globule of fluid metal and the meniscus eflect resulting therefrom cooperating to provide a gas passage across said globule.

6. For an electrical device: an envelope encompassing an enclosure, said envelope being deformed along its length so as to provide a discontinuity in the wall surface of said enclosure; and a globule of fluid metal disposed Within said enclosure, said globule being of such a mass as would normally interfere with the passage of gas contained within the enclosure past the globule in a similar envelope without said discontinuity, said discontinuity and said globule of fluid metal and the menis cus effect resulting therefrom cooperating to provide a gas passage across said globule.

7. For an electrical device: an envelope encompassing an enclosure, the periphery of said enclosure including at least one longitudinal portion having a rapid change in slope with respect to the change in slope of the remainder of the periphery of said enclosure; and a globule of a fluid metal disposed within said enclosure, said globule being of such a mass as would normally block the passage of gas contained 'within the enclosure past the globule in a similar envelope without said portion having a rapid change in slope, said portion having a rapid change in slope and said globule of fluid metal and the meniscus efiect resulting therefrom cooperating to provide a gas passage across said globule.

8. Means for use with a fluid including an elongated envelope encompassing an enclosure having a longitudinal portion with a lateral peripheral outline to which a globule of fluid does not completely conform, the lateral cross sectional area presented by the portion of said enclosure when arranged in a cylindrical cross section being such as could normally be occupied by a globule of the fluid.

9. A relatively small conductive liquid switch comprising: a non-conducting envelope encompassing a liquidtight compartment; a first electrode having a portion thereof disposed within said compartment; a second electrode having a portion disposed within and extending substantially the length of said compartment; and a globule of conducting liquid disposed within said compartment and arranged to coact with said electrodes, the lateral cross-section of said compartment being substantially uniform throughout most of the length of the compartment and being sufiiciently small and the mass of the globule of conducting liquid being sufiiciently large that the globule of conducting liquid would normally occupy the entire lateral cross-section of a portion of a similar compartment Without said second electrode, said second electrode being so disposed in said envelope that said globule of conducting liquid does not occupy the entire lateral cross-section of said compartment but provides a gas passage across said globule by reason of its engagement with said electrode and the meniscus eflect nesulting therefrom to permit relatively free movement of said globule along said compartment.

10. A relatively small mercury switch comprising: an elongated glass envelope encompassing a substantially cylindrical compartment of relatively uniform cross-section throughout most of the length of the compartment; a first wire electrode, a portion thereof being disposed within said compartment; a second substantially cylindrical wire electrode, a portion thereof being disposed within and extending substantially the length of said compartment; and a globule of mercury disposed within said compartment and arranged to coact with said electrodes; the inside of said compartment being sufliciently small and the mass of the globule of mercury being sufficiently large that the globule of mercury would normally occupy the entire lateral cross-section of a portion of a similar compartment without said second electrode, said second electrode being sufiiciently close to an interior wall of said compartment that the mercury engaging said electrode is spaced by the meniscus effect from a portion of the adjacent wall to leave a gas passage across the globule to permit relatively free movement of said globule along said compartment.

References Cited in the file of this patent UNITED STATES PATENTS 1,873,142 Norviel Aug. 23, 1932 1,925,274 Norviel Sept. 5, 1933 2,583,434- Meyer Jan. 22, 1952 

